Sony TC-788-4 Setup guide

DUN Ke
4 CHANNEL STEREO TAPECORDER ~..
TC-788-4
°
OWNER’S INSTRUCTION MANUAL
Precision, uncompromising quatity, and superb quadraphonic or
sstereophonic sound... they are now yours with the exciting Sony
To-788-4,
Spoctal features ar.
415 ips, 10¥/2-inch reel, 4-track 4-channal
operation.
Ac servo-controllad capstan drive motor which provides constant
speed regardless of voltage or load changes.
‘#*Closad-loop dual capstan tape drive which assures postive tape-
to-head contact and isolates external vibration
eLogic-controited function buttons which allow feather-touet,
direct transport switching from any mode to another mode,
Provisions for timer-controlled recording or playback
‘Separate tape equalization and bias salector switches to optimiza
tho characteristics of any tape.
‘*PAN POT (panoramic potentiometer) facility which enables back-
to-trant channol mixing, especially useful for mutt-mie stereo
recordings.
‘¢Synenro-track foeiity 10 allow synchronized recording of new
‘tracks with previously rocordad tracks.
‘#Direct coupling of the playback head 10 the FET in the first stage
of the playback amplifier, resulting ia better signal-to-noise for service-use onl
characteristics.
Please read these instructions carefully to obtain maximum per
formance and enjoymant from your TC-788-4. The tlexiili
provided by its many faatures may not be fully appreciated unless
‘you spond’a little time gaining familiarity with its controls and
facilities. Keep this manual handy for future reference,
jeording and playback
WARNING OWNER’S RECORD
To avoid electrical shock, do not open. the — Fer your convenience, record the model number and serial number
{you will find them on the rear of your unit) in the space provided
cabinet. Refer servicing to qualified personnel pelow. Please refer to thom whan you contact your Sunerecope
only. Service Station in case of dificaty. This wil Be @ great help to
you in getting better end more satisfactory service on your unit.
To prevent fire or shock hazard, do not expose
the set to rain or moisture.
Model No. TC-788-4 Serial No.

TABLE OF CONTENTS
SPECIFICATIONS ........
FREQUENT CLEANING OF HEADS RECOMMENDED
PRECAUTIONS . fe
UADRAPHONIC SOUND
CONNECTIONS...
FUNCTION AND LOCATION OF PARTS AND CONTROLS .
‘Amplifier Section
Tapestransport Section
TAPE THREADING. .....-.....--.-- b
RECORDING AND PLAYBACK a
Fundamental Steps
4-Channe! Recording
‘2-Channel Recording
Playback (¢ CH, 2 CH)
Mone Recording and Playback
Erasing Tape
RECORD LEVEL ADJUSTMENT . oe 14
SPECIAL, OPERATIONS... 18
Micraphone and Line Mixing
‘Mixing with the Use of the Panoramic Potentiometer
Synchro-track Recording
‘Timer-activated Recording
About Tracks and Channels
EDITING. 2
Duplicating Procedure
Cuoing Procedure for Splicing
Splicing Tape
MAINTENANCE.
Clanning Heads and Tape Path
Domagnetizing Heads
Lubrication
Cleaning of the Cabinet
TROUBLE SHOOTING GUIDE...
20
SPECIFICATIONS
Power requirements: 120 volts AC, OH:
Power consumption: 120 watts
Tape speeds: 1Bips, 71/2ips
Recording time: 4-channel stereo recording:
fwith 3,600 ft tape} 45 minutes at 15 ips
90 minutes at 71/2ips
2-channel stereo recording:
80 minutes at 1Sins
180 minutes at 71/2ips
Mone recording:
180 minutes at 18 ips
360 minutes at 71/2/ps
2 min, 30 seo. with 2,400 tape
Fast winding time:
(tOt/2-inch reel)
Reels: 101/2 inches or smaller
Track system: 4-track 4-channet stereo recording and
playback
4-track 2-channel stereo
4-track mono
Heads: } record head, 1 playback heed,
Vorase head
Motors: Ac servo-controlted capstan motor: ......1
I motors
Bias frequency :
Equalization: NAB standard
Signa!-to-noise ratio: 56 ¢8 (SLH tape)
5348 (standard tape}
Harmonic distortion: 1.2%
Frequency responsa: With SL ta
20~26,000 Mz at 15 ips
30 ~ 28,000 He3 dB at 18 ips
20~28,000 He at 71/2ips
90-23,000 Hz 3.48 at, 71/2 ine
With standard te
20- 30,000 Hz at 18 ips
20- 23,000 Hz at 71/2 ips.
0.04% at 15 ips, 0.06% at 71/2 ips, WRMS ‘Wow and flutter:
Inputs: MIC inputs.....es..+ss++04 (phone jacks)
Sansitivity 0.2 mV {=72 48)
Accept low impedance microphones
LINE INputs «0. 4
Sensitivity 0.06 V {--22 dB)
Impedance 100 ka
Outputs LINE OUTputs
Outpot level 0.43 V {6 dB) at toad
impedance of 100 kO with the PB LEVEL
‘control in center click position (PB LEVEL
control set ta MAX: 0.775 V=0 dB)
Suitable load impedance--higher than
tok
HEADPHONE jacks 2
Accept 80 stereo headphones,
AC outlet: Unswitehed 1 {300 W maximum)
Dimensions: 173jetwh x 22{h} « B3}eld) inches
Weight: 68 lb 702
‘Supplied accessories:
1OMzinch reel... 1
Reel adaptor RAD-10 2.2
Connecting cord RK-74H........2.4
1
1
1
Head cleaning ribbon... a
4-channel demonstration tape ...-
AC power cord.
2 subject to change without notice.

FREQUENT CLEANING OF HEADS.
RECOMMENDED
eThe bast performance of your TC-788-4 depends on your
petiodic cleaning of the heads and ail surfeces over which the
tape travels. Cleaning should be done after every 10 hours of
operation,
For details refer to the “ MAINTENANCE” section on
Clean head
FREQUENCY RESPONSE [et 15ins)
T TOT 7
oy stem hese
Hy rset
By ary mead AL
ih Lf LE ES
Output love in 6
LT Even hacaty visiote | \
7 Hil
H
|] aosttaver of 1.5e \
oF 1 13
Udetorioraws freavency
Frequeney in He
Playback wavetorm at 10 KHz
By eloan head
By dirty head
‘The output tevel
fucwates
It you hava any problem with your recorder. consult your nearest
Superscope Service Station.
PRECAUTIONS
Safety
‘@ Operate only on 120 AC, 50 He.
‘@Shoutd any liquid or solid object fall into the mechanism, unalug
the set and have it checked by qualified personnel before oper-
ating It any further.
‘*Unpiug the set from the wall outiet when
for an extended period of time.
‘#To disconnect the cord, pull it out by the plug
the cord.
Is not to be used
Never pult it by
Installation
‘eThe TC-788-4 is designed for vertical operation only.
‘® Good air circulation is essential to prevent internal heat build-up.
Be careful to select a position which allows adequate air circula~
tion, Do not place the sat in an enciosure—ike shelf that would
‘block the ventilation grilles at the back, top. or sides of the set.
Never place anything on top of the cabinet,
#0 not install the set in @ location near hest sources such as
radietors and air ducts or in a place subject to direct sunlight,
‘and protect it against excessive dust, mechanical vibration, and
shook.
Operation
@ Lock tha reals before operating.
‘*Thread the tape without slack and set the tension arms In oper
‘ating position,
‘eMC and LINE sources can be used simultaneously for mixing,
‘but if you want to record only one of thom, turn the feval control
cof the undesired input fully counterclockwise,
‘The following control So koep them in
their normal positions until otherwise stated, and check ther
trom time to time to prevent operation errors:
@ During normal use keep the REC TIMER LOCK lever in the
upper position. This lever should never be used except for
timer-sotivated automatic recording.
® Be careful not to move the REC MODE switches while
recording.
@ Keep the MIC ATT switchas OFF (pushod-in ‘position of the
MIC REC LEVEL controls).
@ Bo aure to turn the PAN POT switch to OFF, if this feature is
not wanted.
® Keep the HEADPHONE ewitch in the 4 CH (2 CH) position.
© Keep the PB LEVEL controls in the center position,

QUADRAPHONIC SOUND
Quadraphonic sound permits the accurate reproduction of music
a itis heard in a concert hall and gives you the feeling of bsing
iramersed and surrounded by sound. 2-channel systems, even in
‘an acoustically ideal living reom, cannot reproduce tha ambience
and radiation of a good auditorium because of their difference in
oom siz and the limitation of the sound source to two diman-
sions. Quadraphonie systems open the third dimension by adding
two channels ‘to the existing two front channels providing the
separately recorded, reflected sound of 2 large hall, and thus
create the special characteristics and ambience pattern of 8 fine
concert hall in your living room.
Furthermore, for popular music, quadraphonic systams permit
Ingtrumants to be lacatsd to the back and sides of the listener,
‘creating the ilusion of being in the center of the musicians, and
thus opan the possibilities to a large number of surprising effects.
CONNECTIONS
‘While making connections, observe tha following notes:
‘#Turn off the amplifier while making connections.
‘insert the cable connectors completely into the Jacks. Loose
connections may cause hum and noise.
‘*For high quality recording use the supplied connecting cords ;
use th red plugs for the right-channel connections and the
remaining plugs for the left-channal connections.
‘eAnach the supplied cord labels to each cord as this simplifies
later checks.
Amplifier connection
For playback connect the recorder LINE OUTputs to the amplifier
tape inputs for discrete or auxiiary inputs). Fer recording con-
neet the recordar LINE INputs to the amplifier recording outputs.
For conventional stereophonic recording or playback only the front
‘ehannel connections are needed,
channel decoder connections
LINE our
Faonr
LINE IN
BACK
ro line
outputs
tre
fh
Bhs
seit
. :
‘
:
Tuner Front Record player
abs speaker

‘Tape duplication connection
A4-channel tape duplication
itd
cord labot
2echannel amplifier connections
une oT
Back
LINE Int
Ack
FRONT
sae
‘
cd
e ? 5
cbined
—
Ee carn tae
a
Ser
2-chennel tape duplication
10 FRONT LINE
OUTpULs
10 tape inputs
|
to FRONT LINE
Wopurs
Recording
to recording outputs
4
TAPE
REC OUT
2-channal amplifier
TC-788-4 ‘LINE.OUT URE IN
.
} 9-6
Duplication
las
Zito oor pu
‘Duplication from
To fine outputs. nether recorder
Power connections
‘Connact the AC INput to a wall outlet of 120V AC by
supplicd AC power cord.
The
AC
OUTLET
is
designed
to
cupply
AC
power
(maximum
300
watts}
to
other
components
such
as
2
turntable,
ete,
This
outlet
is
not
controllad
by
the
front
panel
POWER
switch.
using the
Ground connection
it
hum
occurs,
it
may
be
helpful
to
connect
the
ground
terminal
[a] to en eppropriate external ground.

FUNCTION AND LOCATION OF PARTS AND CONTROLS
Amplifier section

D RECord button
1 recording, fully depress this button, and while holding it de-
pressed push the J button, The red lamp in the button will light
indicating that the recorder is in record mode.
@ REC TIMER LOCK lever
During aormel operation this lever should be in the upper position.
For timer-activated recording slide it down after pushing the REC
button, and the TG-788-4 will record (ond erase} any time the
> button is pushed.
@ FRONT REC LEVEL controls
‘The left controls aro for the left front channel, and the right for
the right front channel. The larger knobs adjust the recording
Jevel of the corresponding LINE INputs, and the smalfer ones
adjust the level of the MIC inputs. Excessively high microphone:
input signals may be attenuated by pulling the MIC contrals out
wards [PULL ATT 20 dB). Normally, however, they should be kept
pushed inwards.
@ Equalization selector (E03
Select the bost equalization characteristics for the tape used, in
both racord and playback modes. Recommended EQ settings for
listed on page 10.
@ MIC jacks
‘Any high quaiity low-impedance microphone equipped with @ phone
plug may be os
priate front and back inputs.
For
stereo
racording
with
more
than
2
microphones
use
the
front
inputs
for
the
extreme
right
and
left
positions,
and
the
beck
inputs:
{or
the
positions
in
betwaen
of
the
reflected
sound,
while
switch-
ing
the
PAN POT
switch
on
(refer
to"
Mixing
with
the
Use
of
the
Panoramic
Potentiometer
[PAN
POT”
on
page
16).
sphonie Tecording use the appro~
@ REC MODE switches
‘Select the tracks to be recorded by setting these switches to REC.
Red lamps in the corresponding VU-meters will Iiuminate indicating
that the channel is ready for racording. For playback set the
switches to the PB position. For synchro-track recording set the
switch(ed) of the prerecordad track(s) to SYNCRO TRAK, and those
‘of the tracks to ba recorded to REC.
@ MONITOR switches
For playback set these selectors to TAPE, and for record level
adjustment sat them to SOURCE, While recording, tape monitor-
ing is possible st TAPE, and source monitoring et SOURCE.
© Panoramic potentiometer switch {PAN POT}
During normal operation this switch should be set to OFF.
Set this switch ON to feed back-channel input signals to the front
channels. The graen PAN POT lamp will light to remind you that
‘the panoramic potentiometars are activated
@ Pancramie potentiometer controls [PAN POT)
‘To feed the input signals of one of the back channels to the left
front
channel,
turn
the
corresponding
PAN
POT
control
to
LF.
To
convey
these
signals
to
the
right
front
channel,
set
the
control
to
RF. The center click position, marked C, directs the added sound
source t0 the center front position. These controts allow the
acoustical positioning of one or two mono sound sources between
the left and right front channel positions.
@ BACK REC LEVEL controls
They function in exactly the same manner as the FRONT REC
LEVEL controls to regulate the back channel record volume,
® HEADPHONE outputs end
® HEADPHONE switch
‘Any high quality 8-ohm stereo headphones {two or four channels}
equipped
with
2
standard
binaural
phone
plug
ean
be
connected.
With
the
HEADPHONE
switch
set
to
4
CH
(2
Ch),
the
Front
head
phone
output
provides
the
front
channel
(LF
and
RF)
sounds
or
the
left
and
right
sounds
in
stéreo
recording
or
playback,
while
the Back headphone output provides the back channel sound (LB
‘and Re} in quadraphonic recording or playback.
In the F+B position of the headphone switch the front and back
sounds
of
the
left
channels
can
be
heard mixed
in
the
left
head=
phone,end
those
composed
of
the
front
and
back
right
channels
in
the right headphone, independent of whether the connoction Is
made to the front o back haadphone output.
When
the
headphone
switeh
is
set
to
MOND,
the
sounds
of
all
four
tracks
are
mixed
together
and
can
be
heard
on
either
chann«
right
or
left,
front
oF
back,
© POWER switch
© Playback Jevel controls {F PB LEVEL ond 8 PB LEVEL)
Thase knobs adjust the playback signal level at the LINE OUT and
the HEADPHONE jack, which ere also shown on the VU-met
when the monitor switch is set to TAPE. A O-VU reading corr
‘sponds
to
an
output
voltage
of
0.43V,
During
normal
uso
set
the
smater knob (R channel} to the canter click position and align the
larger knob with the other one. If the level is 100 high or too
Jow,
adjust
these
knobs:
fuil
clockwise
rotation
will
provide
5
48
boost, and full counterclockwise rotation will muta the sound.
@ VU-meters
‘With
the
monitor
selectors
get
to
SOURCE,
the
meters
show
the
recording
level,
with
the
selectors
set
to
TAPE,
the
meters
show
the
output
level
et
the
LINE
OUT
and
HEADPHONE
jacks
;
0-VU
reading
corresponds
to
0.43
volt.

Tape-transport section
© Tope-height adjusters
If the tape rubs 2 reol edge, the tape height can be slightly
adjusted with thasa screws; clockwise rotation witt bring the tape
closer to the front reel edge, and counterclockwise rotation oloser
to the rear adige. Before adjusting check both eupply and take-up
reels, If thoy are warpad, replace them
@ Tension armas
If both arms are horizontal, the tape-transport contrat circuit
prevents any tape motion.
@ PAUSE lever
For ingtant stop depress the lavar in record or playback mode
(The PAUSE lamp will light). A slight push upwards releases the
fever again.
@ TAPE SPEED solector
For critical recordings, when extended frequency rasponse
and dynamic range are required. 15 ips (38 cm/s) is recommended.
Tiia.ips {}9emis) wil still yield excellent sound quality white
saving tape:
8
© REEL SIZE selector
‘Salect the optimum rewind tancion and reel ‘torque for the reels
used: The 1O1/2 position is for 101/2-inch {270mm} retls, and 7
is for 7-inch (180mm) or S-inch (120 mm) reels. Use the same
kind of reel {size and hub diameter) for both supply and teke-up
side.
@ Tape counter
@ Function buttons
“44 rewind, m stop, p> forward, snd Pp fast forward; these
buttons can be depressed at random to change tape motion from
normal to fast wind and vice versa,

APE THREADING
ite
the
some
Kind
of
reels
(size
end
hub
diameter)
for
both
supply
@For
the
101/2-Inch
ree!
supplied
neither
reel
adantor
ner
spacer
ad take-un is required.
Place
en
empty
reot
on
the
take-up
(right)
side
and
a
full
rea!
Use
the
supplied
reel
adaptors
RAD-10
as
illustrated
to
install
‘on
the
supply
{left}
side.
10t/2-inoh
(270
mm}
metal
reels.
Lock
the
reels
as
illustrated.
Note:
Oo
not
use
the
spacers
for
101/2-ineh
plastic
reels.
Reel holder
|. Thread the tape as illustrated. Be sure to pass the tape under Reel spingle
the tension arm guides, and above the fixed tepe guides.
Reel adaptor
“Turn the outer knob to secure the real to the adaptor.
Tom the inner knob to secure the ree! to the spindie,
€
va
4, Rotate the reels to take up tape slack untit the tension arms
ata
in
thelr
lifted
(operating)
position.
Noto:
When
threading
a
tape
make
sure
that
the
function
buttons:
44, and DP are roleased (Press the MM button}. IF any of
these buttons is depressed and power is on, the tape motion will
start a8 soon as one of the tension erms is moved into operating
position.

RECORDING AND PLAYBACK
The following six control setting should be checked before any Fundamental Steps
recording and playback to prevent operating errors oc undesired
effects, The function of each switch Is explained on page 7.
and 8.
During normal operation {record as well as playback} keep the six
controls in the following positions:
@ REC TIMER LOCK lever .....-unlacking (upper) position.
@ Microphone ‘ATTenustors ....OFF (pushad-in position of each.
MIC LEVEL contrat.
Only for those channels to be
recorded: REC; for the other
ehannels or during playback:
Pa.
@ REC MODE switches.
® PAN POT switch... OFF.
@ HEADPHONE owitch . <4 CH (2 CH).
@ Playback level controls .......Center position forthe channels
(f and & PBLEVEL) to be used and fully counter
clockwise position for the chan-
nels not to be used.
@ Turn the POWER switch on.
@ Thread 9 tape. Make sure that the tension arms are in oper-
ating position
@ Set the tepe counter "0000" by deprassing the reset button.
© Switch the REEL SIZE selector to the appropriate position.
© Sot the TAPE SPEED selector at dasirad.
© Sot the BIAS and EQ selectors according to the tape used:
cas
BIAS solector | £0 selector Tapes
SONY SUPER 180, SUPER A
TDK 150
SCOTCH 160
Other 150-type' tapes
i
\
|
Gon sun
|
Low NORMAL
}
specia, | MAXELLLNE 35
sea AGFA PE 36
BASF LP 35, 35 LH
SCOTCH 203, 206
Hie TDK SD 160
NORMAL }
For recording select proper setting of BIAS and EQ switches. For
playback select EO proper setting.
‘The above six fundamental steps are common to any operation.
For the next staps proceed 20 one of the following paragraphs,
whichever is appropriate: 4-Channet Recording, 2-Channel Record-
ing, Playback (4 CH, 2 CH}, or Mono Recording and Playback.
10